Buds stopped growing

Hey all I am new to this forum and it is my first grow indoors. I have a 4x4 grow tent and I am running 2 1000w Oneo led full spectrum lights with both veg and bloom lights turned on. The temp is between 21C and 23C, humidity is 40 - 45%, ph is right around 7. I am in week 4 of flower and everything was great until recent. The buds seem to have stopped growing, some of the leaves have started to claw and some of the bottom leaves have started to turn yellow. I believe it might be caused by the ph being to high as my tap water is between 7 and 8.3. I have flushed the plant with distilled water to bring ph down to 7. I only give nutrients once every third watering. I am pretty sure the strain is green crack but am not 100% on that because the plant came from a friend of mine. Any advice would be greatly appreciated!