I have no scientific reason to believe this, but I think I may have had negative long term effects from overzealous use of pitocin to manage pp bleeding and a slow placenta by an apprentice midwife. I think I had 3 or 4 shots of pitocin and 1-2 of methergine, for bleeding that was probably within the range of normal and a placenta that was out within an hour. Not that I didn't need anything, but it was clearly too much, especially when we'd agreed we'd use herbal treatments first. Anyway, for several years after birth I struggled with serious muscular problems on my left side that were related to previous chiropractic problems, but were much much worse than I'd ever had before and very hard to kick! I suspect the pitocin because I had a similar very bad muscular reaction on my left side to birth control pills, so I just have a gut suspicion of synthetic hormones.
If somebody doesn't take "allergic reaction" seriously, maybe say you had a "bad reaction"? But definitely don't let it go. Whatever happened to me that started with the birth control pill wasn't any kind of documented reaction and was initially blown off by my health care provider at the time, but it happened, it was bad, and over time it's been thousands of dollars in chiropractic and such getting myself back on track!