I wouldnt bring it inside until your lows are consistently in the high 30's, meaning for many hours. I brief dip for an hour or 2 at say 38ish wont hurt a thing. In zone 8 you might even be able to get away with planting in the ground and added some heat lights or protection during below freezing times.

Put it outside while temps are above 40, watch your watering, maybe give it some food and repot into a better mix next spring.

a combination of the heavy soil and being inside is causing the majority of your problems.

mike

Thank you Mike. Let me make sure I understand. It can stay outside as long as the overnight low is above appox 38? Okay. I've been bringing it inside when the temps dropped below 60, good to know she can handle lower temps than that. Also, what do you suggest I fertilize with and how often? Last thing, do you think this will get rid of the brown spots on the plant (what are they anyway)? Again, thank you for your help.

My variegated pink Lemon saw overnight lows of 27F before I finally moved it into my cold-frame.
Yes, there was some damage to a few thin branch tips, but that's to be expected. Anyhow, even a
sensitive lemon is tougher than most folks are led to believe.

Mike's suggestions are solid.

I don't know what the spots are. Do they have dimension? Are they raised off the plant?
Hopefully the pest diagnosis experts will stop by.

Josh

Got an instant read thermometer? Check your soil temperature. I don't like terra cotta pots; because evapotranpiration cools the soil. Listen to Josh, he lives in a colder climate than you. If I lived where you do, I would surely put the tree in the ground; but that's partly because I know very little about container growing and citrus are so much less tempermental when planted in the ground... for one thing they don't get moved around every 15 minutes... the likely cause of most of your problems. The "spots" on your leaves might be scale; but from your description you likely also have spider mites. Here's a link to citrus scale. BTW, if you treated me as badly as you are treating your tree, I might also hate you!LOL Ignorance is curable.

Here is a link that might be useful: Scale on citrus

I've got a seedling that's similar to pic 2.

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It doesn't seem to be anything major (as in it's not effecting growth), but I do have some tiny black flies buzzing about so it could be those.

Regards
Nick

@Josh, yes the spots have dimension. I can actually scape it off and there is no apparent damage to the leaf underneath.
@Johnmerr, thanks for the link. From that it looks like it maybe red scale on the tree. And,yeah, figured she was justified in her contempt of my care. Now hopefully she doesn't hold a grudge and tell the other plants. Can't have them all turning on me. haha