I have a horrible smell from some of my kitchen cupboards?

Hi. As title. There is a foul smell coming from two ground floor cupboards in my kitchen. I just bought a new home. The smell makes me feel sick and recoil, I believe it is damp but there's no visible signs of mould. Two cupboards along, the waste pipe leaks from the washing machine (under the sink) which I'll address. That cupboard also obviously has moisture but doesn't smell in the same way as the other two cupbaords.. Im terrified I will have to rip the kitchen out. I can't afford to do that. The smell is giving me anxiety, keeping me awake, I'm worried for my and my pets' health and worried I have bought somewhere I just can't afford to have fixed. Smell not present in survey, didn't even notice it when unpacking, just got really bad the last 3-4 days and I don't know who to call or what to do.