Do you still have this sew in installed? If so, take it out. There is a thread about healthy edges and crowns and @
MsLizziA has a thread about it. Let me try to find it.
But, since this was your first sew in, let me tell you this: No matter what any stylist/braider says, they are not supposed to hurt. It's supposed to be secure, not tight. It it burns or tingles and you can't turn your head or blink your eyes normally, have them stop and redo it immediately.
A headache is the telling sign that your edges might come up MIA in the near future. After I found the right stylist, I never get a headache after I get sew ins and I'm somewhat tender-headed.
Sorry this happened. Be back with links.
How Mama Dukes Regrew Hair Edges in 5 Months
Healthy Crown & Edges Challenge