Dextromethorphan aka DXM abuse consequences?

As an adult I abused DXM only (without other drugs) for two years, taking about 300-400 mg at a time seeking dissociation and hallucinations in a misguided spiritual quest. Now clean for over six months, I am still dealing with:

shortness of breath
increased sweating
much slower metabolism (read: weight gain)
phantom body pains
sleeping problems
fatigue
mood disturbances (quick to anger, sudden intense sadness, malaise)
some cognitive impairment (forgetting names, difficulty concentrating)

Good times, eh? Has anyone else experienced any of these symptoms upon quitting DXM? If so, is treatment available?