I am new to having jades, about 1 month I was gifted 4 small of them, over the last 3-4 days I’ve notice leafs falling off and turning blackish at the ends ,? I have not repotted them as I’m not sure how to do that, and also though the we’re doing well. how can I find out what’s going on? Or what should I do? Help!

Is this plant outside or inside?
If it was outside did it ever get below freezing? If it was outside was it in an area where a dog or other animal may have urinated on it ? How wet is the soil ?
Imre
The plant is inside ,, the soil now it’s pretty dry. I couldn’t save one of them, I have two that are making a recovery but have the last one that’s not looking so good. i do have a dog but she Is able to get to the plants as they are high. I’ve done a bunch of reading and videos watching but it’s all contra itself, someone says they need water while others say it’s too wet. now the soil is almost dry. I been afraid of over watering it so I haven’t in a while.
My dog is NOT able to reach the plant**