When you transferred/transplanted to a container, what kind of soil or soilmix did you use? It should have been sandy and well draining. (1/3 sand 2/3 garden soil or something like a cactus mix) Does the container have sufficient drainage holes?
Even if the Sunnis hot, after one day in shade to recover from transplanting, lavender should be slowly acclimated to the sun -- 20-30 min at first, then longer every day to toughen up. Either that of some kind of open weave overhead canopy or lattice could be set up so it gets dappled shade. (I put under a dappled shade of a tree)
It should not need to be watered every day, especially if it is in shade.
It's most likely that it's getting too much water and some root rot has set in.
So, first, stop watering until feeling the soil feels dry when you dig into the soil up to the first joint of your finger. And let it sunbathe but gently -- treat it like an invalid. May be no more than 10 minutes at first.
Tell us more about the soil and container it is in. I wouldn't recommend repotting right away, but you may need to do something.
Learning never ends because we can share what we've learned. And in sharing our collective experiences, we gain deeper understanding of what we learned.