Yes, you should continue with Infadolan and hopefully the skin texture will gradually improve. I do not understand why it happened on your forehead but not on those other areas where you also used a dermastamp.
The problem is that UV radiation damages collagen and it can damage DNA but at the same time it is crucial for our health because sunshine is by far our most effective source of vit. D, which forms in the skin upon sun exposure.
Vit. D is very important for many reasons including proper functioning of our immune system - crucial to remain healthy. Many recent studies showed that vit. D even plays a role in cancer prevention.
Do not excessively sunbathe but do not completely shelter yourself from the sun. Every now and then, expose yourself for about 15 minutes to the sun with enough of exposed skin to get sufficient vit. D.
If you have dark skin, you need to stay about three times longer in the sun, as dark skin contains more melanin pigment which is a natural UV filter.
Thirty minutes of full-body sun exposure causes the synthesis of 10,000 to 20,000 IU vitamin D. Taking such amounts in supplements would be toxic - for a reason not fully understood. The levels are not toxic if trigger by sun exposure. Oral supplementation of vit. D is a very poor substitute for sun exposure. Vit. D, a hormone, really is intended to be created in our skin, not absorbed by our digestive system.