Are you sure the insomnia and the other symptoms were caused by that single citalopram tablet?
Another form of therapy available these days, which is not forced into single session compartments a week, is online. You could look up Betterhelp, for example, and there are other sources as well. You basically email or online chat back and forth with a therapist in a more unstructured and continuous way. It does not cost more than regular 50 min weekly sessions and, I think, some of the sites offer a free initial trial period. I haven't tried it but know many people who have and some find it quite useful. And if you don't like one therapist, can ask for others from the same platform.