white spots and splitting

[teus]

I've had this Peruvian for 2 years now, it grew from 7cm to 14cm now. This year I bought cactus fertilizer and give a dash of it every month or so. I water the cactus in summer infrequently, every 1 or 2 weeks. Lately the sunshine has been strong and I watered it a few times twice a week. Exactly one month ago I moved it to a bigger pot and it seemed fine. Now I noticed the side of the cactus facing the window looks bad.
What happened? Did it swell too much and too quickly and the skin is getting stretched?
Too much fertilizer? Too much watering? The soil drains well. I use premade cactus soil with plenty of pebbles at the bottom for drainage, and the top of the soil seems to dry quickly. I read cacti like watering, but only if the soil drains and dries quickly. Maybe the premade cactus soil remains humid for too long, I read that's why homemade mixes are better.

photos of damage, and how it looked while repotting

[jmoney]

I am not sure what is wrong with your cactus. Perhaps a close up of the problem areas will help us get a look at what might be going on. I have heard several times on the forum that the soils labeled as cactus soil sold in stores may not always be a good mix for cactus. I also don't know how often a fertilizer is needed for cactus but I think that the frequency you are fertilizing it might be a bit much. Another member can advise you on the fertilizer part of this. Splitting can be an indication of over watering. You only want to water after the soil is dried out. Over watering can cause rot, if the soil is damp, swelling, or splitting. I am not very experienced with diagnosing cacti issues so you may want to wait for other members to chime in. Also additional close ups might help us see the problems better.

[iann]

Looks like it got scorched. Shouldn't be fatal, but it looks like you'll be living with those white patches for a good while.

[teus]

thanks for helping out!

Also additional close ups might help us see the problems better.

okay, here goes