it could be both. A cyst is usually red with no obvious head.
A Boil is a skin disease caused by the infection of hair follicles, resulting in the localized accumulation of pus,
If think it is a cyst as it has no visible head and is red and under the skin its seems a tiny bit smaller today but is still a big hard lump under my skin it is very tender feels a bit like a bruise how can i help it to go away.
I have had many cysts before and I learned my lesson to never pop it! Worst, mistake, EVER. It can leave permanent scars and it will take ages to go away, plus it HURTS. What I did to make them go away faster (and I am not a medical professional but this should help) is to keep it very clean and using antibacterial soap to wash it with helps a lot. Don't put any perfumes, scented lotions, hair sprays, etc. on it and try to keep anything like that away from it. Applying cold and slow pressure helps with the swelling and the pain making it go flat. What I did (which was recommended by my dermatologist) is I took a small piece of tin foil and placed some crushed ice in it and applied it to my cystic acne. Apply slow pressure and don't try to punch it. Leave it there for at least sixty seconds. Applying creams instead of acidic liquid forms of acne treatment is less painful and helps it go away faster. Another thing that helps a lot may sound ridiculous but it helps. First clean the the area where the cystic pimple is or just wash your whole face. Then apply a topical acne cream to the pimple, but don't rub in the cream; just put on a small dot or enough to cover the area and leave it. Then take a small band-aid and place where the pimple is with the cream still on it. Do this before you go to bed and when you wake up in the morning remove the bandage and ta-da! The cystic pimple should be nearly flat or less red, or at least some type of progress should have happened. I hope this helps!