I have an inflamed lump under my skin, but there is no drainage at all. just hard un-movable tissue. what could this be?

Abscess: It sounds like you have an abscess. This is a walled off area of infection. If it is inflamed it will need to be drained by a doctor in order to resolve. Please see a doctor soon for exam and treatment.

Skin lump: Usually these are abscesses if it is tender, red, painful or can be a cyst if just hard with +/- tenderness. Abscesses are lanced ,packed and treated with antibiotics. Cysts may be opened,or drained ( ganglion cysts in areas of pressure)or removed. Follow up with doctor/urgent care.