Hi,

I would almost be certain you have some blockage somewhere on the suction side of your system. Do you have any check valves on the suction side?
Do you have any type of restriction that could capture that gunk somewhere between the skimmer and the pump?.....that's almost surely where the problem lies. The pump (impellor)itself could be clogged but I doubt that unless your pump basket was removed for a period of time with the pump running.

Dave S.