Severe alllergic reaction in my American Staffordshire Terrior...any suggestions...please read...?

2 days ago he had a SEVERE allergic reaction 2 something (the vet thinks an insect bite), his face was 2X the size as it is normally. I rushed him to the vet & they kept him for a couple hrs. 2 monitor his condition & gave him a 5mg I.V of Dexamethasone, his swelling started to go down & continued....i gave him 4 tablets of .25mg tabs of the same medication in tab form as prescibed before bed (have been doing so morning & night since) & he woke me around 2:30am covered in hives so i called the vet & had him in by 4am they gave him 2 shots 1 of the same & 1 of Dephenbyhamine? (doctors writing cant read it) & it went down over night, as the vet said i may have 2 give benadryl 12pm the next day, i did, then last night the hives started to flare up so i gave it at 7pm & he woke me again with more so i gave it at 1am and again around noon & now hes getting them again! what should i do and how long can this last they said it should stop. He was bathed in cool wtr. and his bed changed pls hlp