Doxycycline Hyclate and taking time

I took Doxycycline for pneumonia that would not go away 100 mg per day. After 4 doses I was struck suddenly with severe chest pain on the left hand side of my chest at the front, down the middle of my chest and on the left hand side of my back and under my shoulder blade. I was admitted to hospital for suspected heart problem. However, after ECG, XRay, blood tests no evidence of a heart problem was found. On release from hospital I checked the patient information leaflet that was supplied with the Doxycyline and it list chest pain as an allergic reaction to the drug. I also experienced a swollen and sore tongue and breathing difficulty which is taking time to go.