<s>[INST] Hi over the past couple of days Ive been having pain in my lower abdomen and also in my back. I am two weeks late for my period but the tests come up negative. Also every time I stand up I get this sharp pain in my head and I feel like I am going to faint. Lastly, I have recently started to get sulpuric burps. Whats wrong with me? [/INST] Hi welcome to Chat Doctor forum.  Thanks for choosing Chat Doctor. F.  As you describe You have pain in the lower abdomen, backache, and spreads up to the neck when you stand up, and feel like fainting. You are also getting sulfuric burps.  The smelly burps suggest something wrong with the intestines. May be amoebic colitis, Ulcerative colitis etc. Other possibilities are urinary tract infection, or stones in the urinary tract, which can show effect on the pull of the body. The Chat Doctor.  I advise you to consult a urologist for diagnosis and treatment. You may have to go for M.R.I.besides other routine tests for confirmation.  Wishing for a quick and complete recovery.  Best regards. </s>