SO UNCOMFORTABLE
I had to be out out and camara put down throat to see the tablet
I had to have it removed
Disclaimer I'm not a Doctor!
Same for me. Doxycycline tablets, taking at week 3 all OK. But a change of my routine meant for a couple of days I took tablets last thing at night with just some water. After those two days I have the same chest pain, pain swallowing as other users mention. I did some googling and have found some research papers:
1) Doxycycline-induced esophageal ulceration in the U.S. Military service.
2) Doxycycline-induced ulceration mimicking oesophageal cancer
You'll find them on google too.
They both suggest that with treatment it clears up in a few days, and all symptoms gone in a few weeks.
Also that pills should not be taken when lying down, and with lots of water.
I'll report back how I get on in a few days. I'm just taking some Dual Action Gaviscon (thick syrupy anti-acid) and a couple of Ibuprofen for the pain. I will continue taking the Doxycycline (shouldn't stop antibiotics without advice), but back to at meal times with lots of water.
Your situation may be different, go see a real Doctor.