No flowers, or flowers not setting fruit?

Not setting

If it's too hot, tomato flowers won't won't set fruit. Temps over 75F at night, and over 85F in the daytime will do it. For that matter, nightime temps below 55F can inhibit fruit-set. Whereabouts are you? Lack of air movement will do it do. Tomato flowers are pollinated largely by the wind shaking them. Unusual fertilization, such as too much or too little nitrogen can cause blossom drop. Too much, or too little water allegedly has some effect.

I'm in my zone 6

I meant

I meant

NY

There is a product - tomato blossom set - that you can purchase at better garden centers (and probably box stores and ag supply outlets; also online) that can help with this issue. It is a naturally occurring plant hormone and fully organic. It will help if conditions are a bit too cool (but not too hot) or if pollination/fertilization is iffy.

I forgot to add one other cause of blossom drop. Stress. A seriously stressed plant will desperately try to fruit, but won't be able to do so. Sounds like your plant was stressed, but then maybe managed to recover? Might think about that.