Hi welcome to Health care magic forum.
Thanks for calling H.C.M.Forum.
You are a mother of a child of 11 months. You felt a cramping of and on in the lower abdomen. You had sex and it was uncomfertable, and pregnancy
test was negative.
Pain in the lower abdomen and discomfert in sex is an indication of dysmenorrhoea,(pain before period) or may be pelvic infection
, or urinary tract infection
I advise you to consult a gynacologist for diagnosis and treatment. You may need to have U.S.scaning besides other routine tests for confirmation.
Wishing for a quick and comfertable recovery.