involuted/curling leaves/branches - more water-vs.root dmaage

My biggest determinate tomato bush has curling leaves at the extreme edges of some branches. The ones at some tips are curling into balls--but are still very green and supple. Also new branches are curled under themselves. I've got a indeterminate vine right next to it, they have grown into eachother a bit. I did pinch enough and it is bushy for the first 18". It is having no problem, but is taller and not as thick. Also gets a little less sun.
My books say this is from not enough water, too much heat, or root damage.
Now I can water it more, but if something has damaged the roots or something is wrong down there...how can I tell? Are there any tip offs of one cause vs. another? Can tomato plants get TOO MUCH HEAT? It has grown taller than its cage, but I could fashion a cover to cool off from the highest sun. I upped the water yesterday and was going to do the same today. I'm hoping to see a change. However if there is root damage I'm afraid I'm just drowning my plant! The plant has reached a beautiful size and has started to fruit. I don't want to hurt it at this stage.
DiGiTAL ViNYL (no email) Zone 6b/7, Westchester Co, NY, 1 mile off L.I.Sound 1st Year Gardener
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snipped-for-privacy@internet.com wrote:

curled-up leaves: could be insects, like aphids.
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