last few don't look as healthy

[Schmetterling]

Good Morning, this is my first full season of raising monarch, so I am a novice. At the end of last season, I
I successfully raised my first 2 monarchs. So I couldn't wait for spring to arrive, having planted indoors various milkweed. I will cutout much of what I have experienced this year and get to the problem at hand. I have read so many post and thought I would be prepared if any of the unfortunate situations happen to my monarchs. Most of the beginning of the season ran well, but now with some unusual occurrences, I am not sure what to do. I have a large screened enclosure that I use, and have 13 in chrysalis form. I have 4 more to go. 2- 4th instars and 2 that made their J form yesterday. The last 4 do not look as healthy as the previous 13. One of these 2 leaked fluid, and has not pupated. The other didn't make the greatest silk pad and was wiggling around much more that I have ever seen with my others and has not pupated yet either. My question is what is the best precautions I can take. Can these last few effect all the others? I feel maybe I took on too much for my first full year, or maybe I just increased my odds of something going wrong with rearing more this year and is just a part of the whole process. Any suggestions will be greatly appreciated.