Driving Myself Mad

Not really sure where to put this but I'm driving myself mad today, can't take much more of it. Have been obsessing over symptoms (a lump, and my sister's sore chest namely) and have decided the lump is down to lymphatic cancer and my sister's sore chest, well I don't know but I'm still worried. I want the worrying to stop and I can't seem to stop it. I can't stop feeling that something serious is wrong, but I hate it; just need someone to talk to, its eithter this or nhs 24 who I don't think my mum'd let me phone...

Please reply, I can't seem to calm down today, whatever I do.