Sounds like it is overwatered to me. Check the soil before watering...let citrus dry out some before watering again. Also, citrus like regular fertilizer---just be careful never to overfertilize. I use a good slow release fertilizer (Osmocote) at a low dosage, in all of my potted plants. Citrus stakes are also good, esp in containers (if the plant is small, break the stake in half or in thirds and use).

Becky

Becky is right. Citrus likes really good damage. My DML is potted in cactus soil and I water it less than once a week. I fertilize with regular citrus food, but about 50-75% the recommended amount.

In the heat of the summer your citrus might need water everyday/ other day, But now the soil in your pot isn't drying out as quickly and you may only need to water once a week.

I agree, it sounds like too much water for this time of year. Even in the summer, I generally only water mine once a week, but I fill the barrel up when I water.
Citrus are heavy feeders as stated above, but it's best to wait until spring to add fertilizer as it will stimulate tender new growth very susceptible to winter frost damage.

wanda

Thanks everyone for the advice, I'll start my DML rehabilitation program immediately.

Napavinoh

Wanda has a good point too. It's hard to wet a root ball in a big pot sometimes. I fill it up and let it drain two or three times when I do water. I usually wait to water until the top inch or so of soil is dry. That may be every 5 days during Santa Anas or more than a week during cool months.

I had the same problem with my first Meyer lemon. After consulting a nursery specialist I learned that citrus trees (especially lemons) prefer a sandy medium. I was told to use a 50/50 mixture of sand and potting soil (without sphagnum peat moss or perlite) both of which retain water and can lead to over saturation of the roots.
Watering once every couple of days seems like a bit much to me. I typically give my trees a good soaking once every 1 or 2 weeks when the soil becomes almost completely dry.
I'm almost certain that your problem is TOO much water, not a nutrient deficiency. I would shy away from using fertilizer this early. Your plant is relatively new and the soil it's in was most likely pre-fertilized anyways. Fertilizing at this point will probably lead to burning and eventually kill the plant. It's easy to overcompensate and love a plant to death. Be patient and resolve the drainage problem first.

~Good luck~ =/

Sorry. Citrus like really good "drainage".

The potted citrus growers on the Citrus forum really like coconut hull chips which are also used for growing orchids.

I had bought a DML at a 1/2 price sale it was almost dead. It was purchased this summer so when I brought it home I watered it right away. A couple of weeks later the leaves were turning yellow. The poor thing only had but 3 branches and about 10 leaves. I figured the yellow was from not enough water since it was still in the 1 gallon pot. So I transplanted it in the ground (very sandy soil). Then after that every week I gave it a gallon of plant food. Now it is 4 times fuller, no more yellow and is also blooming sweet smelling flowers. I think the sandy soil helps the roots grow and breathe more. Hope this helps your DML tree.