I don't think he's done. I think he's mostly just had bad luck. In the game yesterday he was getting killed because he was just giving up singles in bunches, a lot of which were infield hits, and at least two runners advanced bases on errors.
For the season in 68 innings he has struck out 70 batters and only walked 20, those are great numbers. What's killing him is a .332 BABIP and a 62.2% LOB. Those should both regress to the mean and then he should have a good ERA (~3.8, his FIP is 3.55 and his xFIP is 3.78) backed up by a good offense and a good bullpen. It's been a rough month but I think he's going to turn it around and end up with great strikeout numbers, good ERA and WHIP and a good amount of wins.