Every time I walk or run I get cramps in my calf muscles, mainly on the sides of the calves but I started getting a lump or bulge on one of calves. It appears every time I walk and then it goes down but you can still see it.
Foot instability. It sounds as though you are having trouble with both your calfs. If this is true then, more than likely, you are having a mechanical issue with your gait. The outside of the calfs have certain issues unique to an unstable gait. I would suggest that a hands on examination by a expert in gait analysis may be the ticket.
See a specialist. This sounds like chronic compartment syndrome with a muscle "hernia" but occasionally compression of the artery behind the knee can cause this. Anyone who consistently experiences calf pain with walking or running should be evaluated by a vascular surgeon or sports medicine specialist.