Is toenail melanoma on the nail bed, or within the nail? i had a bruise like spot (no trauma) appear, but was able to cut about half of it off.

It depends: Melanoma can be in the nail bed under the nail or back in the matrix or root of the nail. Get it checked. Melanoma is a serious malignancy.

Likely your fine: And it was blood in the nail. Melanoma occurs in the nail bed under the nail. It can show in the toenail as pigmented or sometimes without pigment.

A streak: It appears as a dark streak in the direction the nail goes. If you have a concerning lesion under your toenail you should see your friendly dermatologist.