I have developed a chest infection this week and despite feeling increasingly unwell decided to leave it until 2.30pm yesterday afternoon before doing anything about it. After talking to the practice pharmacologist he prescribed doxycycline and had the chemist deliver it to me. This is unheard of around here so I was very impressed. I am digressing as usual. Anyway, I mentioned to him about the severe stabbing pains at the back and sides of my head and a green nasal discharged. He said it was my sinuses and was normal with my lung conditions. Does anyone know if this is correct or has this happened to anyone else? I was prescribed Doxycycline because I am allergic to penicillin and also a lot of other antibiotics interact with my anticonvulsant medication. The pains in my head are pretty severe and am a bit worried that all the violent coughing has done something to the blood vessels in my (alleged) brain! Sorry if this is a silly question, but I am still trying to understand a lot of things. Thanks for your help and I hope you all keep better. ..