My feet burn all the time. and it feels like big knot's on bottom. of them. and blisters on the inside of them. its been going on for about 3 years. ?

Fungus or eczema: Burning is a hallmark symptom of athlete's foot (tinea pedis), which can cause "knots" and blisters; but there is a type of eczema called dyshidrosis that can do the same thing. You could also be allergic to some component of your shoes, and there are other possibilities. You really need to see a dermatologist and sort this out - 3 years is long enough to tolerate burning blistering feet.

Burning feet: A burning sensation in feet may also be caused by nerve damage in the legs, also called neuropathy. Although many medical conditions can cause burning feet, diabetes is the most common. Most burning feet treatments focus on preventing further nerve damage and reducing pain. See your local doctor for diagnosis and treatment.