Advice for possibly wild caugth eastern ribbon snake

Hi everyone,

I recently got my first snake with my spouse. We intended to get a captive bred one as neither of us have experience in keeping snakes but there are seemingly no thamnophis breeders in my country. So we bought from a specialized pet store which seemed reputable but when we went to pick up our new snake they just handed him over without any info about him. As the store was near closing time and the shop keeper was busy we had to leave and only later noticed clear injuries near his neck. The injuries look old and have already healed. He also dragged the end of his tail while having it almost coiled. I thought that he might have stuck shed in the end of his tail, so I put him in hand warm water to soak for half an hour. I didn't notice that anything got off but I also haven't noticed him dragging his tail anymore. He also seems very stressed. He barely toungflicks at all and mostly just sits in same position body against heat tape for days in completly open area and just stares at our every move. After that he started nose rubbing the glass profusely and wouldn't stop. I remodeled his enclosure little bit and took out his plastic container hides and made some more natural looking places for him to hide in. After that he has started to use the new places to hide, but he still just sits still and just stares at the same direction.

Is there any advice to make him less stressed and feel more comfortable? His enclosure is 125cm x 35cm x 45cm (4 x 1 x 1.5 feet) old fish tank. Warm end is 31-32 C (90 F) and cool end 22-25 C (75 F) with UVB basking spot in the middle around 28 C (80 F). Moisture is between 30-60% with dry bedding and moist moss "bed" in the warm end. He is about 40cm (16 inces) so I believe is fully grown adult and his tale is very long and dosen't taper very quickly so I think he is male but I don't know for sure. We have tried to feed him some fish and we have left some fish and earthworms in his enclosure overnight but he hasn't eaten. There are two hides in the cool end and one large tunnel type hide which spans from the warm end to the middle. He also has very large water dish in the cool end and smaller one in the warm end because he refused to leave the warm end and once he left he drank a whole lot. The substrate is aspen shaving on bottom crushed coconut husksand sphagnum moss on top. We have mostly left him be but have had to handle him for two occaisions.

Sorry for the winded explanation, but I'm really worried as he seems to be really stressed. Any advice would be a huge help!

Also some pictures of his injuries and tail.