Despite scores from Josh Matavesi and Alex Grove, Worcester saw their winless run in the Aviva Premiership extended to five games as a Henry Trinder try and 14 points from the boot of Cook, added to the late penalty try, saw the Cherry and Whites home.
"I'm lost for words; we've lost late in the game so many times this season," said Hill. "I'm not sure how much more of that the players can take; it's disappointing and very cruel indeed.
"Yes we made some mistakes and yes we missed some tackles but it's so upsetting to lose the game in that fashion.
"I've never known a season like it for late losses and at the moment it seems as though Worcester are on the receiving end of it every single week.
"I don't want to comment on the late incident, I want to watch it first but a lot of players insisted there was cover out there and the penalty should not have been given.
"I need to watch it first but I don't want to say anything at this stage that I may end up regretting.
"I've not said anything to Errie Claassens as yet, he has apologised, and it's not the right time to talk to him because he feels devastated.
"Errie is a lovely man and to get a red card is the last thing he'd do and he's absolutely mortified. I'm not going to say anything to him at this stage.
"We started by conceding nine penalties in the first half which wasn't very good. Our discipline was much better after the break and I thought our players gave their heart and soul.
"I can't criticise the players for that performance - they've put a lot of effort into that performance - we played some great rugby and deserved a win."
Gloucester boss Nigel Davies saw his side react to last week's narrow loss against London Wasps in the best possible fashion and move back into the Aviva Premiership's top four.
But Davies refused to be drawn on the last-gasp red card and penalty try, instead opting to praise his side's performance.
"The important thing is we kept battling and ensured the effort never dropped, which meant we always had a chance and we gave ourselves a late opportunity," he said.
"I always felt we had a chance, even on 80 minutes because of the way we got the ball out wide and we have match winners on the field and given the space Jonny May is always a handful, he's always capable of causing chaos and the decision went our way.
"It's difficult to comment on the decision and the try, what I will say is I'm happy that my team continued to play to the death and if you do that you will always give yourself a chance.
"We've not given ourselves any targets and we're just taking each game as it comes.
"We've done well so far but the important thing is we keep giving 100 per cent and keep giving ourselves a chance."
Gloucester Rugby: Cook, Sharples, Trinder, Molenaar, May, Mills, Robson (Lewis. 74), Murphy, Dawidiuk (Edmonds 63), Harden (Chistolini, 70 (Harden, 71)), Lokotui, James, Savage, Qera (Hazell, 63), Kalamafoni
Worcester Warriors: Claassens, Pennell, Grove, Matavesi (Drauniniu, 61), Lemi, Goode (Gray 63), Arr (Hodgson, 68), Mullan, Shervington (Lutui, 63), Murray (Andress, 68), Percival, Schofield (Gillies, 60), Betty, Kvesic, Cowan
Tries: Trinder, penalty
Conversions: Cook 2
Penalties: Cook 4, Mills 1
Tries: Matavesi, Grove
Conversions: Goode 2
Penalties: Goode 2, Gray
Referee: David Rose