Robbie,
Hydrogen peroxide will NOT boil an infection out. The irritation of the gums, if related to the fillings, should be gone by now. You mention that your stress level is high right now. There is a condition called Acute Necrotizing Ulcerative Gingivitis (ANUG) which can many times be brought on by stress.
You have to realize, that even as a dentist, I can tell you what might be going on, but in order for you to find out for sure, you must be seen. With your new symptoms eg the raw gingiva, pain under the tooth, etc. you should make an appointment with your dentist.
Jerry