I had hypersensitivity to pain from black toxic mould. Very nasty neurotoxin! I just slightly bumped my arm and severe pain! I also had red bumps on my inner forearm, excessive thirst...and a very long list of other symptoms. It is hard to say what is causing your symptoms but a common cause of excessive thirst is diabetes. High glucose is toxic to nerves. Not sure if diabetes causes hypersensitivity to pain though.
Go to a primary care physician. I am not a med pro, but have you considered auto-immune possibilities like psoriatic arthritis, given the skin bumps. Extreme thirst could be a symptom of a lot of bad things, and not so bad things. Go to a doctor and get checked out