Swollen lymph nodes

Hi, so I've been experiencing a lot of symptoms Recently, I had an urgent 2 week ultrasound last week due to unintentional weight loss, that came back normal, I've had multiple blood tests they all came back normal, I'm currently in the process of being diagnosed with POTS as well. But in addition to this I've been experiencing a lot of swollen lymph nodes now they are all soft and mobile, I have one in my groin which appeared about 2 months ago, and get occasional swelling in my armpit with occasionally dull ache/ same with my groin. I've not got one on the back of my neck, I went to the gp with my other symptoms when she did the urgent referral but wasn't conceded about the lymph nodes, now the only thing that concerns me is I know lymph nodes swell when you have an infection, I have had no infection nor any signs of infection so I'm just a bit confused as to why they have appeared and why they sometimes cause an ache, I thought I would come on here not because I think it's cancer just to see if anyone has had any similar experience. I'm only 18 so would be appreciated if people could respond as soon as possible. Thank you xx