How worried should I be? Lumps.

Hello! Sorry for the late night post, but just wondering if I could get some insight on some things because Google isn’t proving particularly helpful, and is honestly just serving to stress me out even further. 

I have 4 firm lumps, 3 of which on my head and the 4th on my bum, all of which that have suddenly appeared and grown fairly large over the span of perhaps 4 days maximum. Not necessarily painful, but tender and tingly. Just the one lump would’ve been pretty scary for me, so to suddenly find 4 has been pretty unpleasant. 

I am, of course, quite stressed out about this but not sure if I’m overreacting or if there is something here that I should seriously be worried about. I’m booking a GP appointment first thing tomorrow, but was hoping I could perhaps get some thoughts and advice from people and hear whether or not I should be as worried as I am? 

Thank you so much for reading! I am of course not expecting anyone here to diagnose me, and apologies if I come across like that’s what I’m seeking, just in need of some advice and comfort on the matter.