Edit: thank you all very much for your time, thoughts and effort to reply to this. I really appreciate it and I try to find a new doctor.
Your questions and encouragement were very helpful and made me realise that my symptoms are too strong, considering my lifestyle. For those who asked questions, here are the answers:
I eat healthy, we cook fresh, colourful food almost every day, only drink water, coffee, tea, no alcohol, no smoking, no fast food.
I walk my dog several times a day and when I'm doing something where I have to sit for an extended period of time, I take a little walk evey hour or so and also use a standing desk attachment to change my position. I sleep on a really good mattress (my partner struggled with our last one so we invested in a good pair of matresses, matching our body type)
I have a healthy weight on the lower end of the scale. I had to cut back my exercise that I was doing for twelve years due to the pain, switched to light Yoga and streching until even that became unbearable.
Thinking about all this together, I think my fear of not being taken serious made me believing my current GP.
I'm in my mid twenties. My body seems struggling, since May/ June, so some time then I went to my GP. His response: "everyone experiences symptoms of their ageing body at a different time, seems like you just experience it earlier..." This was around May/ June, it just tends to get worse. Which leads to the questions featured in the title. My body hurts, like, a lot. Especially my low back/ sacrum. My knees, shoulders, wrists, ankels. My hands are swollen in the morning and they hurt, I can't unscrew any lids or bottle caps, sometimes can't even write anymore as my fingers are very stiff. As the rest of my body. I can't reach for anything on the ground in the morning, it makes everything so difficult. I can't really bend over to tie my shoes or pick something up. I can't do my regular activities even though I really want to do my sports like climbing which I really like. I do like being active and want to stay fit. But it just hurts too much. At the same time, resting somehow makes it even worse. I'm exhausted, but need to constantly move around on a low level. How is everyone else doing this if this is what ageing feels like? How am I supposed to have kids or even just live like this, as I always just hear that with an ageing body, everything just gets harder every year? I really do appreciate everyone who reads this. Thank you in advance for answering if you have any tips on how you manage this
Well that sounds rather unpleasant. Maybe I was a little naive in assuming that this doctor for sure won't tell any bullshit, as he seemed (~~old~~) experienced. I'm glad you had the courage to get a second opinion