Filter Pressure Low

[nanupam]

Hi All,
Introducing myself as a new owner of pool. Never had any relationship with pool equipments other than glancing at those while at local gym. I live in NJ.

We had our pool opened for summer about 2 weeks ago and since water is still pretty cold we didn't even use it once yet. Pool guy had set filter to run about 10 hours every day and it was doing just fine. Since Monday (Mem.Day) the pool motor started making weird sound and since I wasn't sure I stopped the filter and vaccum. It seems like when we start the filter water flow coming in from valves to the pump is very slow and it is in cycles. For a minute it will run fine and then again slow down. I did the backwash without any benefits. I see water going to little glass bottle where you see muddy water during backwash. This happens while it is running through filter. Any ideas, where do i start? I will really appreciate any help. Water is stale for five days and I would like to get the filter started soon.