Repair the broken glass in tge greenhouse & put a sulphur candle in there, that should see anything off, then the water butt as advised, after that you’ll know whether it’s an outside thing. For your skin try protecting it before you go out with something like you’d buy for going abroad, used to be called jungle something or other, I had to use it when I took on my Allotment as got bitten by everything but horseflies made me rather ill.