can be antyhing and some people get a bit of the so called test flu. its a period where the body is getting used to hormones and it usually passes quickly. nothing serious in any way. test flu has got zero to do with way of pinning, its a hormonal aspect.
how you pin may cause a local swelling and infection if the needle etc isnt clean so always make sure to work with super clean items, you are injecting things IN your body