Pat Fischer said yesterday that the condition of the pinched nerve in his lower back has worsened. The Redskin left cornerback, who has missed the last two games, said he has found it difficult to walk at times, much less run, during the past two weeks.

The ailment, which hit Fischer during training camp and resulted in his being hospitalized in traction, now affects the lower part of his left leg as well as the hip area, he said.

Fischer said that daily workouts aggravate the injury and his doctors are unable to explain why the pain comes and goes. But he said a decision to end his 17-year Bational Football league career is entirely up to coach George Allen.

"I can't change the thing. He knows it; I know it," Fischer said after yesterday's closed practice, which he missed. "I'm not going to make that decision (to retire) . . . . I'll just play that by car. We need him; there's no doubt about it."

Gerard Williams, a third-year man, is a fine prospect to play left cornerback in the future. But Dallas quarterback Roger Staubach showed how casily Williams' inexperience can be exploited with 50 and 59-yard touchdown passes against him in Sunday's 34-16 Cowboy victory.

On the game-breaking 59-yard to Drew Pearson. Staubach gave his wide receiver a hand signal . . . We prepared for him. He must really be hurting not to have played against us."

Hardly anyone gave Fischer any chance of overcoming the pinched nerve. But, after missing the season opener, the feisty Fischer played well against Atlanta and St. Louis.

He came back to practice Tuesday after St. Louis and his troubles began again.

"I was hoping to be able to practice at least once a day," Fischer said. "I thought we had it: now I'm not so certain . . . I'm paying a terrible penalty for trying to practice.

"Why does it come and go? They (the doctors) don't know why. What's causing it? They can't tell me. I was warming up for the Dallas game and I was able to run. Monday I was hardly able to walk."

Allen said he held Fischer out of the Tampa Bay game to rest him for against Dallas because he had not against Dalls because he had not practiced all week.

The Redskins play the Nwe York Giants Sunday at RFk Stadium and Fischer is listed as questionable on the team's official injury report to NEL headquarters.

Meanwhile the Redskins went to work to shore up the fullback position and the special teams in the wake of injuries to John Riggins (knee) and Bob Brunet (contorusions of the spinal cord).

Eddie Moss, the former St. Louis Cardinal who was a late preseason cut, participated in his first regular-season practice as a Redskin yesterday. He will be used mainly on the special teams and as a backup at fullback to rookie Clarence Harmon.

Calvin Hill, Harmon and Moss worked at fullback yesterday.Running-back coach Joe Walton said that Harmon had only minuscule practice time at fullback. He ran mostly from tailback during the preseason and early regular season prior to and ankle injury.

Allen said Moss looked good during his first practice, although he's a little out of shape.

After the Redskins cut him. Moss, a five-year NFL veteran, went home to St. Louis and began looking for a job. He had not found employment when the Redskins called him Monday, although he was waiting to hear about a possible position as a deliveryman for United Parcel Services.

Moss said he tried to keep in shape in St. Louis by jogging and playing some basketball.

"I wasn't working: I wasn't doing anything," he said. "It feels great to be back. I have a lot of things I have to polish up on. I want to do a good job for the Washington Redskins.

"They had to think something about me to call me back. I'm going to give 100 per cent every play I'm in."

Moss played only two NFL games in 1976, when the Cardinals re-signed him late in the season to replace an injured player on the special teams. His strong special-teams play was the main reason the Redskins brought him in at this point, a Redskin official said.

Three major personnel changes are in store for the special teams this week, assistant coach Paul Lanham said.

Brunet, special-teams leader, will have to be replaced. And so will Williams and Harmon because of their new roles as starters.

Moss. Ted Fritsch, Joe Harris and Mark Murphy will receive additional assignments on punt, punt-return, kickoff and kickoff-return teams, Lanham said.

Quarterback Billy Kilmer, who suffered a bruised left shoulder against Dallas, practiced yesterday and looked better than he did a week ago, according to Allen . . . The injury report contained only one minor surprise - defensive tackle Dave Butz's suffered back spasms as a result of the way he was walking in an attempt to protect the ankle. He is listed as probable, as are defensive tackle Bell Brundige (sprained left ankle), linebacker Petc Wysocki (sprained right foot), reture-man Eddie Brown (bruised ribs) and Kilmer. Fischer is listed as questionable, linebacker Chris Hanburger (knee) doubtful, and Riggins as definitely out. Guard Ron Saul, who came out with a bruised knee against Dallas, was not listed on the report.

Running back Mike Thomas, whose left-hamstring problems have caused him to miss most of the preseason and regular-season practices, came out of the Dallas game in good shape and took part in all drills at full speed yesterday, Walton said.