This what you are describing is an infected abcess.
What happens is the hard spot is the body's way of blocking off the infection, the body creates the fluid because of the enzymes and white blood cells breaking down the infection, eventually this creates a hole in the muscle and the worst thing you can do it try to pop it. This can push the poison/ infection deeper in the muscle.
One must go to the doctor and get this taken care of. They will cut the abcess open, treat the infection and leave the wound open to let drain for a few days then pack with gauze.
I never let mine get this bad because I knew what they were, on day 4 I started popping vitamin c and antibiotics like candy. Luckily I was able to rid this infection and never had to go to the doctor. But I was on the verge of going at one point. Don't let this happen, horrible experience .
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