You have a myriad of symptoms and am unable to lik all these together for one diagnosis. It is likely that all are unrelated apart from the rashes on the neck and red raised bumps that is likely to be urticaria
You may have fibromyalgia
but it is important that you exclude other medical causes before coming to that diagnosis.
Blood tests such as CBC, ESR, Liver profile, ANA, lipid profile
, fasting sugar, TPO antibodies
, thyroid profile would be a start. U/S abdomen for your pains + UGI endoscopy
to exclude GERD.
Only then one can try and get to a treatment plan.