My(21M) stuttering has come back hard after maybe 5 years with very minimal stuttering

My(21M) stuttering has come back hard after maybe 5 years with very minimal stuttering My stuttering was terrible when I started highschool. I didn’t know anyone and couldn’t finish a single sentence. My form personal tutor was a language teacher aswell. Every morning he’d take attendance by calling out names, and in response; students would say “Si Senior”. The register was in alphabetical order of the surnames and my surname starts with a Z. So I was last. Every single day, I’d dread my name coming as I’d have to say si senior, and I found words beginning with S SOOO difficult. And without a doubt; every single day I’d spend a good 2 minutes hissing Sssssssss until the words came out. Eventually my tutor said to start a couple of names before my name gets called out, so that when my name is called out, I’d respond just in time. It became a joke that I enjoyed I guess. Anyways, stuttering hasn’t really been in an issue since that year. Now I’m 21 and at university. But ever since this lockdown began, this stuttering seems to be coming back and it’s pretty bad. I start a sentence and choose a word to say. I come to say it but it just doesn’t come out and I’m left there thinking of another word to replace it. I assume it’s something to do with stress or confidence. Just venting about how annoying this is. I’ve set this flair as venting but if anyone has some advice I’d really appreciate it.