I am a 38 year old male, my primary doctor has me on MS Contin ER 30 mgs, three times a day and Morphine IR 15 mgs, prn for disc damage, herniations in my neck and upper back. He has me on venlafaxine 125 mgs, 1 time a day for mood and nerve pain and Metoprolol 25 mgs for high blood pressure and irregular heart beat. I saw my doctor for a full body rash that often cause large welts and blisters, he treated me with a topical cream used to treat scabbies, didn't help! Now over the last week and a half, I have quit taking my pain medications, as it seemed to reduce the itching and flare ups, but no relief for my constant daily cronic pain. I've also been experiencing dizziness, light headedness, diarrhea, shortness of breath and fatigue. I assumed that I was experiencing these symptoms from no longer taking my pain meds, however, I've not experienced any "withdrawl" symptoms either. It's very important that I find a resolution to these issues, as I am the sole provider for my home and family. I just don't have time to be "sick," as I also maintain a full time position as a Maintenance Supervisor with responsibilities that are more demanding than most other multi-housing complexes. Any advice, information or guidance will be and is gratefully appreciated. I can be contacted at <removed for privacy>.

Have you thought to visit a different doctor for a second opinion if some of the medications your other doctor are giving you do not seem to be working? Also have you explained these problems to your doctor?
Which pain meds have you discontinued.. all of the medication you had listed? (morphine, venlafaxine, and metoprolol)
I can give you some side effects from these drugs:
Morphine: dizziness, respiratory depression, hypotension, nausea, vomiting, itching, sweating
Venlafaxine: anxiety, dizziness, headache, worsening depression, weakness, drowsiness, abdominal pain, diarrhea, nausea, vomiting, hypertension, itching
Metoprolol: fatigue, weakness, anxiety, depression, diarrhea, nausea, vomiting, bronchospasm, rashes, back and joint pain, erectile disfunction
Referenced from nursing central, Davis's Drug Guide

You could be experiencing these adverse effects..
I would as well assume you are not getting any pain relief as you indicated you have discontinued taking your pain medication..
Also do you check your Blood pressure and pulse frequently?
I would strongly suggest you visit your health care provider.