pH problem with soil grow

I woke up this morning and as normal went to check on my plants. This morning I noticed one of the plants was begining to get yellow in the middle of the top leaves... it did not look like nute burn, water issues, etc etc, so I decided to check the water run off for the first time (I know, I know, I now see the importance of keeping up with ALL pH levels!, including run off) my strips only go down to 5.0 and the color was lighter then that!!!! So of corse I'm fruitin' now, I decide it was time for me to try my first flush.... I used tap ph'd water to about 7.5 and flushed it 4 times, the ph remained 5.0<<.... until the last flush, it went up to 5.5. Now here's my question, I know I'm stressin the beejezus outta my plant by the flushes, should I give her a rest and continue to flush next watering or should I keep flushing until I get ph to 6.5-6.8? Thanks guys/gals.

what kind of soil are you using? store bought or homemade mix?

Miracle Gro w/ perlite.... I know that's my problem....

Might be time to repot. Sounds like the buffers might be used up.

careful because a drastic change in ph will also stress your plant u wanna change it little by little

.... so I'm guessing because the ph was too low that my nutrients began to lock out, as a result my leaves have started to do some shadey stuff.... the center of the middle leaves (not the old leaves, not the new leaves) are turning copper colored and buring from the center outward. I observed the same leaves on the opposite side of the plant on the same "finger". A couple days ago I began to notice black spots on some of the leaves, well upon reading up and looking at pictures I believe I have a boron deffic. probably because of lock out. Right now this plant is in the ICU, wilted sad leaves, discolored ones, etc. Hopefully she'll pull through.

She's not dead! and she has had no new signs of nute def. Further, she started growing again. I have been using a foilar spray once a day to give her some nutes while she drys out. Her pot is getting light, I'm gonna feed her tomorrow, as far as the dead leaves, do I trim the dead leaf only, or the cluster of five? Also, are there any ideal times to trim? Before feed, after feed, morning, night, etc?

Her soil is still acidic, 5.75, her waterings and feedings will now be ph'd to about 7.2-.3. I know I have to watch her runoff close. I just ordered a ph and ppm meter, should be here within the week. (Side rant: Lol, I started this little project to SAVE money, ugh now I have to pay for this AND medicine... I know it's gonna be worth it someday! I thought I was starting a nice little "hobby", ya right, more like an obsession! <<<seriously about to get divorced.... jk.... well I hope..... Even though all the problems, I love growing, I like being around the plants, the smells of fresh foilage, green lush leaves, pretty cool. My "little" hobby turned into a multiroom operation!)

So far so good, I'll update.
....now off to attempt to save my hydro gro.....