Hi
If night sweats are related with the nexplanon implant you should see your GP about it as it been longer than 2 - 3 weeks generally that it should be happenening if at all ok. There is many side effects that is possible although few may not get any.
As you been having these night sweats since July last year then certainly speak to you GP on this.
I'm a NHS nurse but obviously can't give medical advise on here as reason why I said go and speak to your GP.