Please help with my limequat tree!

[limehound]

I have a new-ish dwarf limequat tree, that didn't arrive in the best condition and has only got worse.

-First I thought it was citrus greening, because of the small bugs and the twisted and colour of the leaves, but you don't get that in this part of the world.
-Then I thought that it was a nutrient deficiency so I gave it nutrients intended for citrus, with added Fe and Mg, but the tree is now flowering but still doing worse.
-The leaves are turning brown and red.
-The bugs are also getting worse and I can't identify them. Maybe they're doing well from the added nutrients.
-There are also small, black 'pock marks' on some leaves.
-I've also given it Confidor insecticide (imidacloprid) but it hasn't had any effect.

Can anyone please help me identify the cause of any of these issues??

Thank you!!!

[Millet]

Your tree could be showing a manganese deficiency. This is more or less common at this time of year. All of the leaves showing this deficiency pattern are the tree's newest leaves, while the older leaves remain green. As this is container grown tree applying manganese sulfate or manganese nitrate will correct the deficiency. If the leaves are dwarfed from normal size than it is a zinc deficiency. In this case a zinc sulfate solution will quickly cure the symptoms. What fertilizer formulation are you using?  Besides the macro elements required by citrus, does the fertilizer also contain all the trace elements needed?

[Yorgos]

Those aren't psyllids, which are the vector for HLB (citrus greening).  Look to be fungus gnats or something innocuous.  Fungus gnats in small numbers are harmless though in high numbers in a pot might chew on a rootlet or two.

[limehound]

Your tree is showing a manganese deficiency. This is more or less common at this time of year. All of the leaves showing this deficiency pattern are the tree's newest leaves, while the older leaves remain green. As this is container grown tree applying manganese sulfate or manganese nitrate will correct the deficiency. What fertilizer formulation are you using?  Besides the macro elements required by citrus, does the fertilizer also contain all the trace elements needed?

Thanks @Millet, really appreciate the input! The fertiliser is NKP 9%:3%:3%, with trace elements iron 0.02% and magnesium 1.5%. It's beginning to flower a lot so I presumed that maybe it was doing ok with nutrients and it was the insects, but I'll get hold of some manganese and see if that resolves the issue.

The new leaves come out very lush and green, and then eventually turn (one of the photos I attached was from a week or so ago whereas the others were all new)

[limehound]

Those aren't psyllids, which are the vector for HLB (citrus greening).  Look to be fungus gnats or something innocuous.  Fungus gnats in small numbers are harmless though in high numbers in a pot might chew on a rootlet or two.

I too wondered if they were fungus gnats but they seem a little large (around 5 mm), and there are quite a lot of them but the imidacloprid doesn't seem to be affecting them...