Severe burning sensation under feet?

Could be. Plantar fasciatis or neuropathy. See your podiatrist for a treatment plan.
Neuropathy. You could have neuropathy. See your doctor for an examination and blood/diagnostic testing to find out the cause. There are many treatment options currently available to control the symptoms ranging from ointment to pills to implant stimulator...The most important thing is to find out why you have neuropathy.
Neuropathy. You need to see a doctor to find out the etiology as there are many reasons this can occur.