Senators, reeling from a bloody showdown over the budget and facing a possibly bruising fight over raising the debt ceiling, are being hit by the House where it really hurts--in their bank accounts.

As the Senate was bogged down on the budget last Wednesday, the House Appropriations Committee inserted in an otherwise routine $4.8 billion supplemental money bill a provision that would limit senators' outside earnings to about $18,000 a year, 30 percent of salary.

Under a deal agreed upon by the House and Senate last year, House members raised their annual pay by about $9,000 to $69,800 while senators kept their pay at $60,662 but removed their cap on outside income. House members, most of whom do not make much money from speeches, kept their $21,000 limit on outside earnings. But, as senators' financial disclosure reports began rolling in this month, showing that at least 15 of them earned more than $50,000 from speeches to outside groups, House members began to have second thoughts, at least about the senators' end of the deal.

"I think we have to take care of our brethren over there," Rep. Silvio O. Conte (R-Mass.) explained solicitously as he proposed the new 30 percent cap on senators' outside earnings, without mentioning any rollback in the pay increase given House members.

"Here we were being buffeted around on the pay increase," legislative subcommittee Chairman Vic Fazio (D-Calif.) said yesterday. "And now we're getting tarred with the same brush. We clearly have a perception problem on this."

If, as expected, the House approves the proposal when the supplemental appropriations bill reaches the floor later this week, House members may have more than a perception problem.

Fazio said that he has heard that the Senate may try to retaliate by repealing House members' pay increases, which could cause the House to drop the whole issue when the bill gets to conference.

The bill is needed largely to continue funding for mandatory programs, such as food stamps, that would otherwise run out of money before the fiscal year ends Sept. 30.

It would also provide money for repairing and extending the West Front of the Capitol and put a temporary ban on leasing government coal reserves, which a report for the Appropriations Committee has charged are being leased at "fire-sale" prices.

The Capitol extension is also expected to spark controversy with the Senate, which has historically favored simply repairing the existing structure.

Meanwhile, the Senate girded for possible resumption of its fiscal troubles in connection with House-passed legislation to raise the federal debt limit $99 billion to a record $1.39 trillion.

Treasury Secretary Donald T. Regan reiterated yesterday to Senate leaders that the extension is needed by May 31, when the government will need more borrowing authority than the current limit allows.

The budget battle, won by Democrats and Republican moderates, left "some hard feelings out there" that could spill over into the debt debate, a leadership source said. Some senators were reportedly eyeing the debt measure as a veto-proof vehicle for final action on the repeal of withholding on dividends and interest.

With both houses scheduled to recess for a long Memorial Day holiday later this week, it could be "very, very difficult" for Congress to meet the debt-extension target date, Majority Leader Howard H. Baker Jr. (R-Tenn.) warned.

The budget fight continued to reverberate yesterday as House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) sent a letter to his colleagues accusing President Reagan of "distort ing the facts" in claiming that his spending cuts have not hurt people, blaming Congress for deficits and saying that his economic program has worked.

O'Neill said that benefits have been cut for 900,000 college students, 13 million recipients of school lunches, 20 million food stamp beneficiaries and 960,000 welfare clients. He also said that the recession, coupled with Reagan's tax hikes and military buildup, have added $825 billion to deficits in the four years from 1982 to 1985.