Do you know anybody else with it?
It is remarkably common with up to 80% of people experiencing it during their lifetime, but it really is not noticeable to other people as you think it is.
You will probably find it spontaneously improves during the sunnier weather, especially if you keep your arms uncovered (no need for sunburn though).
You may find this useful.
There is no cure but the British Association of Dermatologists recommends the following:
Avoid excessive dryness of the skin but emollients and moisturisers are of limited value. That is not to say that they have no value.
Creams with salicylic acid, lactic acid or urea may be of value.
Expensive cosmetic or vitamin creams are not helpful.
An abrasive pad may be helpful.
Take tepid showers rather than hot baths.
Calcipotriol is not of value.
The best thing you can do is forget about it and enjoy your summer. Nobody else will notice.