so yeh this is my first post on this site, been playing poker for 3 years now (im only 19 so started young-ish). took a major downswing in january so havent played for a while, but i decided to play some omaha again (my strongest game by far), was grinding it out for about an hour, got up from $30 to $200 on .25/.50, then this happens...

  (donkoff in BB)
  (me in SB)

flop comes 

i bet, he raises, then i re-raise and he pushes, i call eventually thinking im against diamonds

turn is 
river is 

he makes backdoor low end straight, on the flop he had up to

basically, was it a bad play by me to call with the middle set, having seen him donk off most of his chips with no hand and missed flush draws i thought i was good? or was i just unlucky on the turn and river... haha

to make things worse, 2 hands later, i get  and after re-raising a reraise, guy calls with    3

flop of  , i bet 3/4 pot, he pushes and i instacall, and no help on the turn or river, god i hate pokerstars haha