Basic FHA guidelines allow for a housing ratio up to 31% of your income and total debts of up to 43%, however, these figures can be exceeded if your loan can be underwritten using FHA's automated underwriting system AND if the lender permits it.
Find out from your loan officer if this loan requires manual underwriting or will accept an automated decision. If it requires manual underwriting (as many 203k loans do) then you are probably out of luck unless you can pay off and close some credit lines. If the lender will accept automated approval you need to find out if DU or LP approved the loan at the higher debt-to-income. If so, then the issue is probably a lender issue or requirement and technically you could seek another lender.
But at the end of the day I'm not so sure the seller would be accepting of starting the loan process over elsewhere. So you should do your best to try and work things out with the lender you are with. Lean on your realtor for advice and influence as well.
Best of luck. 203k loans are a pain and few lenders do them well which is why most lenders shy away from this business. Hopefully you have a good, experienced lender.
Let him know Tony Taylor referred you.