Last week i felt a lump pop under my skin on my calf and a day later i had a huge bruise. i can still feel something hard in the same spot. serious?

Huge bruise: Yes, it is serious and I strongly recommend that a friend or family member will take you to the nearest Emergency facility. You will almost certainly get excellent advice an care!

The lump may have-: -been a cyst of some sort. With the rupture there is bleeding , hence the bruise. If a clot is formed it can be due to fibrous remains of the initial bleed.