welcome to healthcare magic
first of all you should immediately stop masterbating or atleast till your bump heal
will lead to sexual under performance by way of premature ejaculation
, as well as other sexual problems.
Normally, masturbation is a healthy sexual behavior. But like other behaviors , when over practiced it (maximum 2 times a week) can lead to both psychological and physiological imbalances
your bumps are due to high capillary pressure filling during masturbation process which might cause cap tear and swelling/ulcer.
if it not heal then consult to your doctor to get some antibiotics and anti-inflamatory drugs