I've been on the 3 monthly Prostrap injecs since Jan 21 (just alternate which arm it goes in); lots of the side effects which were occurring regularly for me during the initial period (including hot flushes, aches in joints etc etc) seem to have settled down now, get an occasional flare up in the week or so following the injection but nothing overly onerous...just 3 or 4 more to go for me now; hope it works out for you, if it doesn't there should be alternatives to try as described above.
Rgds,
Nick