Pain in back of left knee, calf, hamstring & buttock. tingling/numbness in heel. gets worse seated. no swelling or discoloration. ican still exercise?

Tingling: It is possible you have sciatica, compression of the sacral nerve and worse when sitting because your compressing the nerve. If you keep on having this you should get a MRI spine of the lumbar region to evaluate if this is the case.

What the heel is it.: Continuing to exercise at this point may inadvertently do further damage to the nerve involved. Would be best to get a evaluation to safeguard against prolonging your condition.