Changing lip piercing jewelry?

I will have had my lip pierced for a month on Friday and I know the healing time is 4-6 weeks. Mine seemed to be completely healed after about 2, so I changed my jewelry out (the stud they pierced it with is huge and the post is too long) after 3 and used the same size gauge stud, but as opposed to having a ball like my first one did, it had more of a flat diamond. The new jewelry really seemed to irritate my piercing, making it feel tight, itchy, and hurt to open my mouth wide. I switched it back out with the original stud and everything is fine again. Could it be that I changed the jewelry out too soon and my lip wasn’t completely healed yet, the new stud was too small or a combination of the two?

fine jewelry