I've been 'Into' and out of Chastity for about 10 years now. I've never really worn any of my devices for really long periods. For me it's a way to curtail my masturbation habit when it gets out of control. Here is 2 things that I have discovered over the years. My balls are 'High and Tight' this means that when they are pulled through the ring and the tube is shoved up there, they are cosy to say the least. Nothing is squished, but there is not much wiggle room. I have experienced 2 kinds of Scrotal pain. 1. The nocturnal erections result in the base ring pulling forwards and trying to rip my balls back through the ring. Very painful, it is eased by greasing up before sleep, but ultimately can only be eliminated by the erection subsiding. 2. Scrotal dryness. Over my lifetime, I've had dry skin on my scrotum maybe 3 times in total, one time it was so bad, it was like dandruff, with skin flakes. This year, I'm working my way though locktober, and after a week by balls began burning. Literally like they were on fire. Close inspection showed some redness. I slathered them with hand cream, and it helped, but ultimately it required a day and a half out of the cage, covered in cream to soften the skin once more. (For those interested, this was not used as an excuse for a release. I'm still 10 days backed up!) Just some feedback I've learned over the years. Look after your family jewels.
For the scrotal burning in the short term, I swear by Aquaphor. It's petroleum jelly based, so fairly long lasting - but also with aloe and skin friendly stuff to help heal. Overall, I also have high-tight balls and found what I need is a larger "gap" between the ring and shaft. Most cages default to about 10mm, I need 15 and went custom partly because of it. Very much worth looking into.
I read a tip about Shea Butter on here recently and now I love the stuff, give it a try: https://www.amazon.com/dp/B00CGIC5IE