Hello and thank you for your question.
From what you have described, it sounds like your son may be having more than the expected local soreness following vaccine administration. A small, non-tender lump in the muscle is common, but it is usually no larger than the size of a peanut. This type of lump resolves in about 1-2 months but doesn't cause pain with weight bearing.
It sounds like your son is having a local skin infection in the area of his vaccine. This occurs due to bacteria from the skin surface entering with the needle of the vaccine. Infections typically present as redness, tenderness and swelling after 48 hrs of vaccine administration.
I would call his doctor to have him seen as soon as possible. If the doctor's office is closed, you should take your son to the emergency room. He most likely needs antibiotics.
Fortunately, these types of infections are uncommon with the administration of a vaccine. There is no need to withhold further vaccines in the future. I hope this helps. Feel free to ask any additional questions that you may have.
I'm glad you took him to see his doctor and that all seems ok. I was concerned about his level of discomfort.
Best wishes to you and your son!