I noticed a huge lump under my armpit since monday and from monday up to now it has grown twice its size and is very painful if touched/moved. helpp?

Abscess / boil: You need seen by a surgeon. Can start w/your dr / urgent care / er, mostly for antibiotics and pain relief, but will need incision to drain pus / reduce swelling and pain.

See your doctor: The painful lump could be an infected lymph node or hair follicle. You might need antibiotics, and sometimes the infection needs to be drained.