Help! lumps under my feet?

Possibly Plantar Warts, the doctor can freeze them off with liquid nitrogen

If it is a plantars wart there are many over the counter remedies that are slower than seeing your doctor but still effective.

If it is more like a squishy lump, like a pimple as you say, it is likely because of some irritation to your feet such as if you have suddenly changed your activity level and your feet are reacting by trying to pad themselves! Try staying off your feet for a while, soaking them in warm (not HOT) water...

If you have a fever or if the bumps get bigger then unfortunately it is a big deal and you need to go to the doctor because they may need to be lanced. Additionally if at any point you see something like red streaks creeping up your leg, that is an emergency and you need to go to the ED.

May not be anything, but as you say, being a diabetic you have to take great care of your feet... Here in England , My wife, diabetic, had regular chiropody treatment from the local health authority.. She had an appointment at the foot clinic every two months. Biggest problem likely to affect diabetics is reduced circulation causind gangrene, also the presence of sugar in the blood makes infection of little sctatches etc. much more likely.

I agree plantar warts, they can be quite painful and although they usually will disappear on their own it can take up to a year. There are over the counter wart removers specifically for them but it doesn't always work. A trip to the podiatrist will get rid of them usually in just one treatment and in less than one week.

Dont worry its called a Corn, you won't need to go to the doctors, just to the pharmacy to get some special plasters.

i had one on the side of my foot but its gone now!

Sounds like a blister. I had one of them once that didn't go away for about 2 months or more. It was VERY bothersome but eventually it went away.