He may have swiped right to make you a match on Tinder because he was seeking attention from you.
This is a guy that has already shown a lot of emotional instability and has even admitted to you in the past that he is on anti-depressants.
This emotional instability is often what tends to make him desire attention.
Seeking out attention may be his entire reason for being on Tinder in the first place.
After all, he hasn’t shown the emotional capacity to do what it takes to build and maintain a relationship.
You have already experienced his desire for attention in the past when he wrote on social media about feeling as though he didn’t belong on the planet because of his lack of friends.
He was hoping for sympathy and attention.
You provided it to him when you checked up on him and he consequently told you not to worry and that he wasn’t looking for attention.
He actually was.
He yearns for attention.
However, he isn’t willing to take any action to develop a relationship.
This is why he rejected you in the past and continues to ignore you at school.
Building and maintaining a relationship would be too much of an investment in time and emotion and he simply doesn’t want to put himself in that position.