Help!what’s going on with this plant?

It would be helpful to all of us if you'd link your question to a diary so we can see "the whole picture" ... Don't know what you're growing (autoflower? photoperiod?), don't know the age, don't know the nutes, don't know anything except that you have a problem... and you DO have a problem if this is not simply a matter of the plant nearing the end of it's life... Offhand, I'd ask what the pH of your runoff is... you say the OTHERS don't have the problem but in my experience, each plant reacts differently so you may have some nitrogen toxicity going on... if the pH of the runoff is below 6, you're going to want to do a flush and then introduce nutes back at 1/2 strength... I would suggest you link your question to your diary and ask it again...