Ok - one problem at a time:
1. Depression/OCD type behaviour - get back to the psychologist or see a new one
2. Difficulty swallowing: the response you're getting from your MD and dietician is not acceptable. To be "unconcerned" about her swallowing issues tells me they're not treating one of the largest areas of human quality of life - completely unacceptable.
Has she had a Modified Barium Swallow Study? If not, insist upon it. It will tell you WHY she's not getting fluid down - it may be there is a tightening of the esophagus which won't allow fluid to travel down to the stomach (a dilatation could improve that) but it could be that the larynx isn't lifting up high enough to trigger a swallow - if that's the case then going through the discomfort of a dilatation procedure will be of no help at all. Treatment to get those swallow muscles active and elevating could help the problem. So you see, it is very important to know the WHY of the problem before you determine a solution.
3. The rinsing - WHY is she doing it? Is it because she can't swallow her saliva, does her mouth feel dry all the time so the rinse serves to moisten her mouth? The constant rinsing can be an irritant and serve to dry out her mouth more. If she can't swallow then she has no choice but to spit. If she can swallow - she should. If she needs more moisture there are products that are similar to saliva - artifiial saliva - that would be much better for her to use if it's a moisture issue. After 8 months, she's devloped the habit of spitting and rinsing - it would be a lot of effort for her to break the habit by using an oral mosturizer and forcing (essentially) herself NOT to rinse and spit constantly. It could take a while but the end result would likely be a return of the normal balance of the mouth and she might not feel the need to rinse at all.
Swallowing is a poorly understood issue, one that the medical community may be a little slow to address - please, PUSH it!