Well I'd say you definitely went off the deep end. What ever possessed you to put that much H2O2 (Hydrogen-Peroxid) in the water? You might as well have sprayed 3% directly in your eyes and of course anyone who has inadvertently done this knows it burns like hell.
I believe you are having a MAJOR cleansing reaction. You have all the classic symptoms of it. Breathing that much H2O2 (Hydrogen-Peroxid) in an 8 hour period can certainly cause the lungs to hurt from the detox. It's roughly equivalent to sucking on the output tube of a medical ozone generator which also is not a good idea.
You might consider upping the intake of antioxidants to lessen the effects of the detox/oxidation reactions gong on in the body. Vitamin C is a good one. 1 gram per hour is not out of line until the symptoms lessen or you get diarrhea. If you do get diarrhea, go back to the the dose you took just before it happened.
Hope this helps