Sudden,Intense Pain?!

Recently, my left lung would have a brief and sudden moment where I would breath and an INTENSE pain would occur. I have no clue what this is... I don't have asthma, I don't think I was having a panic attack. The one that really struck me was this morning. I woke up, went to use the bathroom and came back to lay dow. A few moments later my left lung started this pain. It felt like someone was stabbing me every time I went to breath... I'm afraid to goto the doctor and they tell me I'm fine. I'm clearly NOT Fine. I'm not making this up. Why would I want to be afraid to breath cuz I fear the pain is going to be there?