Hi - I'm sorry your DS is having trouble. My DD (9) is currently dealing with anxiety.
It's very hard and stressful - we've started sessions with a counselor but so far it doesn't appear to be helping. I did have her do an online anxiety course for kids that seemed like it would be helpful (GoZen). However, although she enjoyed it and seemed to get the message (she spent a therapy session explaining all the strategies to the counselor), she seems unable to apply them a lot of the time.
Not advocating medication, but just relating something that may be helpful - My DD is also extremely taste and texture sensitive. However, my husband managed to teach her to swallow pills by having her swallow very small candies whole - he took her to a frozen yogurt place where they have a variety of sizes - from sprinkles up to larger ones. They started with the smallest and worked their way up. When she can do this it's very helpful because she often refuses liquid medication. Of course sometimes she also refuses pills (due to anxiety) but sometimes it works.
Everything you've said is very familiar, including stubornly refusing a therapist's suggestions.
I hope you find something that works for your son.
