Hello, thanks for asking you query at this forum.
I am doctor Alok Sinha from India and I will try my best to reply your question.
Most probably you are suffering from a
fungal infection. Tear on foreskin is mostly due to friction, excessive moisture, prolonged sweat etc. Frequent
masturbation and intercourse without much lubrication are the common causes. It commonly occurs in persons suffering from diabetes/obesity.
Since you are already obese (300 pounds), have
jock itch and there is recurrence of these tears on penis, you must take it seriously. You get yourself checked well by a physician who may investigate you for diabetes,
dyslipidemia,
hypertension etc apart from prescribing you some anti-fungal cream/tablets for cure of localized fungal infection. You should seriously try to reduce your weight below 200 lbs over a period of next few months to reduce the chances of future recurrence of illness.
I hope it answers your query. I wish you all the best.