Yellow Seedling with spots

I can't see the spots. Just what looks like a lot of burn and you listed the causes: lots of rain (leading to over-watering), lots of sun (too much which with the excess water sucked up too much fertilized soil, and both the sun and fertilizer burned your plant). You might have a fungus infection like leaf septoria buried under the light/fertilizer damage. The three remedies I've used are hydrogen peroxide, baking sod, and milk. You don't need to use all 3 but people who use milk/baking soda will often use one one week, the other the week to avoid messing up soil ph and salt build up. My current grow had leaf septoria, which is what you may be describing. I killed it with a hydrogen peroxide solution, then switched to baking soda/milk until I was certain it was dead. When it is, there's no restoring damaged leaves and when the plant was healthy enough to defoliate, I removed those four original leaves as I had a lot of new growth. Now, on day 28 and just going into flower, you'd never say there was ever a fungus infection as the plant recovered fine. But you need to do something to protect it from excess rain, wind, and sun and kill any fungus. In the right ratio, hydrogen peroxide, baking soda, and milk are all effective against fungus and cannabis safe (hydrogen peroxide would be my first choice there).