Hi there ~
I understand your concerns. The hard knot after injecting meth
was probably hematoma
or a collection of bleed when you hit a vein or a veinule. I also believe that using warm water worsened the condition and it will probably take some time to heal at the current rate. I believe that the bladder infection has nothing to do with the hard knot after injecting meth, however the antibiotic may help in the way that it may not lead to infection of the hematoma and abscess
formation. However, I recommend that you consult a qualified doctor to make sure that your condition does or does not need medical attention. In any case, you definitely need treatment to get off of meth addiction and a psychiatrist
would be the right doctor to consult.
I hope this helps. Take care and have a lovely day!