Hi.
Thanks for your query.
Noted the history about an 18 year old male having
constipation, green stools, lower back pain, blood blisters like rashes on arms, legs and stomach but only one at a time and that goes away on its own, sharp pains in sides...
This can be a serious problem.
I would advise you the following:
Get a clinical evaluation by a
General Surgeon.
Tests of stool, urine and blood.
A course of an antibiotic,
metronidazole,
probiotic and supportive medicines like that for pain and spasms.
If there is complete relief, nothing more may be needed.
If there is no complete relief, you need to see a Gastroenterologist, go for further tests of
colonoscopy and CT scan of the abdomen.
Further treatment will be as per the findings.