I'm sorry, I haven't been getting alerts for some reason. Just saw this.
I really don't know what the spot on the wing is, feather follicle is certainly possible. I think it likely the other issues with her wings are from her trying to use them to balance and move herself.
Crop issues and the poop are concerning, maybe the Baytril will help. I don't know where you are but Marek's is not usually a reportable disease. Culling a flock is generally up to the owner, most labs consider Marek's to be endemic. There are many, many, many people who have Marek's in their flocks, and many who try to breed unsymptomatic birds in order to end up with birds that are genetically more resistant to the virus. I know about the PCR test from a small blood sample, I've heard of testing of a feather shaft/follicle but don't know who does that, the only other way I know is by professional necropsy. People who send birds in for necropsy often get results that say Marek's is the underlying reason for death even though the actual symptoms were of something else, since Marek's can really weaken the immune system leaving them susceptible to other things. Sometimes Lymphoid Leukosis presents symptoms that are similar to Marek's, as well as some vitamin deficiencies. I hope you get some answers and that your vet is helpful. Honestly, any information that you come away with would likely be helpful, no matter what it is.