Swimming Head Pressure w/ Cold - Head Bump

[snavemaill]

Hello, I've been suffering from a cold for the past few days and I went for a swim tonight - My nose wasn't stuffed up, but as soon as I put my head under water I felt a quick, sharp pain in my temple and had a vice of non-painful (yet uncomfortable) pressure over the top of my face and around my head - it quickly subsided whenever I brought my head up. What could be causing this? I'm talking right beneath the surface of the water - not deep at all. Also, I've been worried about a large, slightly raised spot on the top of my skull. It is hard in nature, and when I put pressure on it I freak myself out to the point of feeling slightly lightheaded. It's been there for a while, I can't tell if It's growing but I have no idea what It could be since I haven't been suffering from headaches. I'm afraid it might be something serious. Is there a part of the head anatomy that presents itself as a raised spot at the very top-center part of the skull?

Thank you for any advances on this.