Cut by a dirty blade a month ago and today neck's blocked , not sure if it's my gym or tetanus ? when cut no inflam signs , took amoxillin after cut.

Not tetanus: The incubation range for tetanus is 3-21 days with most evident by 8 days.It also occurs with in infection at the primary site. It is likely your workout is responsible.

Depends: if you had your tetanus vaccine aka dT within past 9 years, you should be fine. if you are not up to date on your vaccine, then you are probably still ok b/c tetanus wouldn't show up a month later. It would be faster. Most likely gym. Go see a trustworthy chiropracter.