It could be the early feeding. Or it could be something else. You never mentioned the pH of your water / first feed. And need to know more about your soil as well. Brand? Added amendments? at this point, if you handed the plant to me and walked off, I'd do a slurry test of the soil,
and then nothing but pH'ed water till after transplant (which I'd probably get right on). Honestly, in soil, you can usually go way lite on feed until entering flower.
Slurry test is 1 part soil from container to 1 part distilled water. A tablespoon or so of each is fine. Let sit a couple moments and then test pH. Should be 6.4 to 6.6 or not far off.