is the tree always in doors? and how much sun does it get in a day and how often are you watering and fertalizing?

I use a water gauge, so I do a deep water about once a week. It's always indoors, on account of not having any green space (I live on the third floor of my buildling), but I use a grow light for eight hours a day. Thanks for taking the time to read my post! :)

I'm far from being an expert, but I think the next question will be...What are you using as a grow light?

The leaves look like simple edema, caused by too much water when the plant is too cool and not growing enough to absorb it.

If you google "edema in container citrus", or edema in potted plants, you might learn how to fix it.

If that doesn't work, you will have to rely on some of our container gurus to help you; my expertise is only in Meyers inground.

I think John is right.....It looks like past disasters that i have had......leaf drop from the ground up and then twig die back......Too much water......In fact i would go as far as saying poor drainage.
what happens is the mix compresses and stays wet and the roots suffocate due to lack off oxygen......It is often caused by over watering and the compacting of the soil.
I found adding inorganic particles to the mix helped provide air spaces and excellent drainage.....Perlite was my choice.......I once read an article from Israel where they grew citrus in large pots with different grades of perlite and thats all....it was at a shopping centre.
The question now is.....can your tree be saved?
If you get some fresh mix(this mix will be going stale)....some of the roots will be brown and smell......prune any yukky roots off.Still should be some good ones...prune the dead twigs off in relation to your root prune and mix some fresh potting mix with perlite.....repot.....water once(see how quick it drains) and leave it alone.....do not add fert to new mix.......keep out of direct sun for a couple of weeks and do not feed until you see some new growth and then only with a weak solution....always water first....then liquid feed after that....keep pot up off a tray with pot feet to aid drainage.
If this fails....buy a fresh plant and learn from the experience....i killed so many citrus trees like this.....too big pots and soggy soils......the inorganics help prevent compaction when first transplanted and give the roots the channels they desire to fill out into the pot.....once compacted....there is very little air spaces left...another option is terracotta as the breathe but they also dry out very quick in the heat......Give it a go...hope this works for you.....
Little tip....make sure the pot is 2 to 3 inches bigger all around than your rootball.....once you have completed the pot and before you water...lift the pot to feel its weight.......then water and feel its weight then.
Dont water again until it feels light, like when you first lifted it up.This,plus the perlite in your mix will keep you out of trouble.

Laidbacklord gave some great advice as well as others!

The soil is always the first suspect with me then everything else....

Mike