Hi and welcome to this community
Briefly put, in case-control, we split the sample according to the outcome (for example, the result of smoking [cancerous/non-cancerous patients]), and in retrospective cohort, we split the sample according to the exposure (for example smoking/not smoking]).
But your design is none of the above. It is a clinical trial, in which you are assessing the effect of an intervention. It is similar to a retrospective cohort, however, instead of exposure (like smoking, sunlight, etc.), there is an experiment. So your case seems quite a clinical trial.