Yes, those negative test results are a relief for you.

There are infections, that affect the nerves. One is common from poorly cooked chicken called Campylobacter. It can affect the nerves. It was highlighted on Wrong Diagnosis on Discovery Channel. Some of those shows are available on the net, if you want to find it.
http://www.cdc.gov/nczved/divisions/...campylobacter/

We do get people here who have developed PN symptoms following viral or bacterial infections. Some do get better but that takes a year or more usually. That is little comfort for the present though.

I would get that arsenic looked at .... arsenic causes neuropathies. Look under "integrative" or "environmental" doctors on Google for your area for that. Most regular doctors don't know much about poisons.

I hope for your sake you don't have some result from those endoscopes. If you see an integrative physician be sure to tell him/her about them.

I'd also go gluten free, for at least 6months to see if you feel better. It might be revealing and helpful for you. Get that Kefir, too. And integrative physician will test you for Candida. The aldehydes that this yeast makes puts a terrible strain on your system giving all sorts of confusing nerve symptoms. Benfotiamine (a form of B1)300mg a day may help you if you think you have Candida. It supports the enzymes that remove aldehydes from the blood. Your bloating, nausea etc could reflect that. Doctor's Best brand is a quality one that is affordable as well.