RO Membrane Giving High Output TDS

We own a 2000 ltr/h water treatment plant and it was working fine till two days ago. We were  getting < 100 mg/l TDS with 2500 TDS of raw water and ~4000 mg/l TDS of wastage water. Now all of sudden the RO membrane (DoW made BW30-400) is giving high output TDS of ~200 mg/ltr while the raw water is still having same TDS. Output wastage water TDS is now around 3000; it was around 4000 previously. What could be the reason for this sudden increase in TDS?  I don't think membrane can stop working all of sudden. I tried cleaning the membrane and it gave 130 TDS for 2 minutes and started increasing after that to 200 again. Please suggest what to do?