Sorry to hear you have this as a side effect. I have very sensitive skin and photosensitivity (not medication related). I know how hard it is to find the cream that works for you, but when you do, it's super.
The one that works for me is La Roche Posay Anthelios Comfort Cream
http://www.laroche-posay.ie/product-treatments/Anthelios/Anthelios-SPF-50-Comfort-Cream-p10059.aspx
It is a bit pasty at this SPF, but a bit of tinted powder over top can help both with colour and shine. The factor 30 in this is also really good but I understand that you need 50.
They also have a stick that I use for a bit of extra protection on my nose (also good for tops of ears/anywhere you tend to burn). I find it helpful because I can layer up on my nose - stick then cream and then top up with stick as needed.
If your skin isn't dry, you'd probably get away with this version, which may be less visible:
http://www.laroche-posay.ie/product...elios-XL-SPF-50-Ultra-Light-Fluid-p10057.aspx
If you end up liking that range/it suits your skin, it's worth knowing that it's much cheaper in mainland European countries, and they often have larger containers, so you can send friends who are going on hols off with a list!
This is a sun allergy range I tried a few years ago that my skin did not like at all:
https://www.pizbuin.com/en/our-products/allergy
I haven't tried Avene but could be worth it. I did find an Avene balm that works for my skin.
Something it took me many years (like, over 30!) to discover is that many companies will give you your money back if you have an allergic reaction to their product.
Time of exposure makes a big difference for me too - morning before 11 and evening after 4 are best for me. In the middle is just asking for trouble. And amount of exposure is key too - it works a bit like pacing, for me, if my skin sees the sun in the morning, it needs a break for the rest of the day, and it needs rest days. Once the photosensitive rash comes up, I need absolutely no exposure for weeks or it just comes right back up again.
Hope some of this is helpful!