Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Emergency care may be appropriate for inability to pass urine, fainting, confusion, or signs of a severe allergic reaction after medication, such as trouble breathing or swelling of the face or throat.
Arrange routine medical care promptly for any new genital ulcer, even if it is mild or not painful.
Also contact the treating clinician if symptoms do not begin to improve within several days, the ulcer returns, or a recent partner has not been evaluated.
Seek urgent medical care for rapidly increasing swelling, spreading redness, fever, severe pain, heavy drainage, or difficulty urinating.
A foreskin that is trapped behind the head of the penis and cannot be returned to its normal position also needs urgent attention.
A follow-up visit is generally recommended three to seven days after treatment begins.
The clinician will check whether pain is improving and whether the ulcer is starting to heal.
Lack of improvement does not automatically mean something serious, but it does require reassessment.
At follow-up, the clinician may reconsider the diagnosis, repeat testing, look for a second infection, review whether the medication was completed, or consider antibiotic resistance.
Large ulcers and groin abscesses may need additional time or drainage.
The article also says
If the initial HIV or syphilis tests were negative, repeat testing may be advised because early infection can be missed.
CDC guidance recommends repeat syphilis and HIV testing three months after a chancroid diagnosis when initial results are negative.
The timing may be adjusted based on the exposure and tests used.
Every sign above is quoted from the sofidex article on Chancroid. If you are not sure, err upward — it is always reasonable to be checked.