I'm making a 2d-platforms game, and I already made the engine, with paralax scrolling, three layers, some sprites and colisions.

The problem is the colision with the platforms (ground, walls, etc.). I already made it, I check 2 or 3 points on each side of the sprite to see if it collides with any wall. If it does, I do not let it go any further. The problem is...

Do you know this platforms you can jump from below??
How can I manage the collisions with this kind of platforms efficently.

thank you