The lump or knot on the bottom side of my tongue hurts and this pain started when i was taking antibiotics, steroids, & potassium pills?

Possible stone: The knot under your tongue could be a small stone in the opening of the submandibular (wharton's duct). Does the jaw swell when you eat? This would be confirmatory. Otherwise, you could have a mucous retention cyst or inflammation of a minor salivary gland. Have an ENT check it out. No worries! good luck and good health!

This maybe...: Unrelated to the meds that you were taking. A swelling near the tongue should be examined by your dentist or oral surgeon.