Please Help With a Few Worrying Questions

I have a few questions and would be extremely grateful if anyone could help me out.

Ok, firstly:

i’ve posted this first question before, but I would like some other people’s opinions. When I was about 15/16 and started noticing these tiny groups of spots appear on my penis. I’m un-circumcised and they started to appear towards the top of the back of my penis going in a downward direction. Since then they have spread all over my penis shaft, under my penis head and near the tip. They’re pretty small, but very noticeable, they’re just a bit lighter than my skin colour, they’re always in bunches, very close together and cannot be popped.
I’ve been to see a few doctors about them, one doctor said they were ‘normal’, one said they were ‘sweat glands, a lot of people get them’, another one said he thinks it’s like a skin condition and another didn’t say anything.
I’ve only just noticed that the places where the spots are, are the parts of my penis that rubs against the penis head whilst masturbating, I also believe that around the time of 15/16 is the time I in fact started masturbating, but it could just be a coincidence. Could anyone please shed some light on this?

Secondly, for many years I have noticed that my scrotum seems to change a lot, for example when I do exercise it seems to tighten and my testicles go up into my body. This also happens when I need the toilet, usually when I need to crap (sorry, couldn’t think how else to put it) but as soon as I have finished on the toilet, my testicles come back out and my scrotum relaxes again. I also think this happens sometimes when I am nervous. Is this normal?

Thirdly, recently i’ve been noticing a few bumps on my penis head, you can’t feel them, and you can just see them when you catch them in the light. Also every now I then I keep getting a few pains in my penis, I think it might be the head, it doesn’t ache, it’s more of a stinging feeling, but it soon passes. Could this just be ‘one of those things’?

For a few years i’ve had some what of an obsession with thinking there’s something wrong with me, 90% of it is a fear of having testicular cancer, even though i’ve had 2 checks by the doctor and one scan, however nothing was wrong. A lot of the time I uncomfortable with my body, especially ‘down there’, I think it’s because i’m not 100% of what’s normal and what’s abnormal. I just want to clear a few things up so I can hopefully enjoy a regular and healthy life.

Thanks to anyone who helps me out with this, it is very much appreciated.