Lemon trees are tropical or sub-tropical;
they cannot survive outdoors even here in north central Texas, let alone in Ohio.

Bring it inside, spritz it with seaweed solution (you can get it at any organic nursery), keep it in a warm sunny room...

& you might check the Tropicals Forum for more expert advice.

I wish you the best!

There's a Citrus Forum here in Gardenweb. I'll attach a link for you below. I highly recommend that you make a visit to read up on the challenges of growing citrus in containers.

I suspect that your lemon is simply going through a normal disgruntled phase after having been brought inside. Even though it's way too cold for citrus in your location, they still prefer plenty of direct sunlight and the outdoor humidity. They will typically shed their leaves to teach you a lesson.

When we drag them kicking and screaming to our living quarters, they sulk for months. You can mitigate the stress by providing artificial light and humidity. You can learn what others have done in the Citrus Forum.

Once you do a little homework, we can also help you with your potting medium, identifying pests, proper watering, and more.

See you over there!

Here is a link that might be useful: Let's find out about your lemon tree!