Hello, I am new to the group and I am hoping someone can help me with my lemon tree. I have a Meyer lemon that I have been growing in a container for 2 years. Recently I have noticed the leaves becoming "yellow-spotted". I recently fertilized it with a citrus fertilizer spike & don't know if this is the problem or if it has a disease. Any help is greatly appreciated. I have attached a couple of photos.

It looks like a deficiency that the fert spike may or may not rectify.
I don't recommend using the tablets or the spikes as they don't give a balanced dose of nutrition to the whole tree. Half may get a little or none while the other gets a lot. I use a granular slow release fert with micros and apply all the way around the tree so it all gets what it needs. The spikes are also not designed for use in containers and can cause fert overdose. IF possible I would remove the spike, flush the pot with a whole lot of water and apply a granular fert in a month . Choose a good fert with micros. You can use Osmocoat, or Peters, or even one at your local nursery.

Molybdenum defiency causes the yellow spots your tree is showing but so do a few others. The molybdenum defiency shows up in the older leaves only as the new growth takes what it needs from the older ones.
Hope this helps.
Andi