Sounds like you are growing too fast...errr..yea
These are caused by rapid enlargement and appear when the skin becomes overstretched and the fibers in the deep skin layers tear.
Anyway, these are permanent. They will turn white after a while.
I am glad you brought this up, cause my muscles are ballooning and last time I went from 145 to 200 staying at 11% BF...I got some nice stretch marks
Back then I made a salve to apply to them and they stopped "running" yea, they were like runs in a stocking as the muscle grew.
Options..Coco butter or shea butter or elastin cream applied topically as per the label do help.
Or make your own:
1/2 cup virgin olive oil
1/4 cup aloe vera gel
Fluid from 6 capsules vitamin E
Fluid from 4 capsules Vitamin A
--mix together very well...in a blender works (to clean the blender, use your hand and wipe the excess on your growing muscles where the stretch marks appear (biceps, hips, thigh, pect/delt underarm area)
-- put this in a glass jar..preferably a dark glass jar and store in refrigerator.
Apply once a day every day to prevent further stretch marks.
Thanks for reminding me to pull that recipe out!