How long does pericarditis last?

I am an 18 year old male with pericarditis. I am wondering how long it lasts? i have been on ibuprofen, oxycodone, and i am currently taking sulindac 200mg for inflamation (inflammation) and pain. The pains are very severe but i seem to only notice them in the night. I went to the e.r and was told i had pericarditis but my cardiologist said everything looks fine. i feel the pains and i know i am not fine. i get very short of breath every day, and i always feel like i have a "lump" in my throat. I was also told by e.r doc that i have a murmur. How long does this last and is there something else i ca do to stop this. it has gotten in the way of me doing good in college and other things. All replies are greatly appreciated

[Cleveland Clinic]

It can last for months, in rare cases. You need to take the anti-inflammatory medications ( motrin or aleeve) on a regular basis so that the inflammation has a chance to subside. If this does not occur you can have grave long term consequences, including the rare condition of constrictive pericarditis. You should also have a repeat to check for presence of fluid in the pericardial space, and to make sure the diastolic function of the heart is within normal parameters.