Just water with lower ph, don't need to flush unless it is looking really bad.
your trimming then straight into flower is probably what did it, always should allow a week or two in veg before flipping if you have just stressed the plant, but no biggie it's all a learning curve.
my 4 clones darkstar and sage n sour are looking great and the 2 northern lights are slowly coming up (small stems, poor cuts). Just need to baby the NL a bit. Other than that going to check on my outdoor grow today, I put the other wwxs#1 and sns over there, probably just going to see if they can survive and get small harvest from them.
3 plants left in hydro are doing well, they had a bit of nitrogen toxicity when I boosted the nutes, so I eased off and adding ph water only to reservoir to bring the nutes down a bit, will flush with 1/4 strength next change and then keep them around 950-1050 ppm till week 4 (the darkstar and sns are much higher nute hogs than the wwxs#1, it seems very touchy)