If you search on the web, I think that you will find many sites that will help explain what you are seeing, I found a website (keep in mind that this is one persons opinion) that had some good explanations on it;
http://www.mendosa.com/injector.htm
""Jet injectors are not suitable for everybody," says Vitajet President Sergio Landau. He says that people who are very thin often can't use it."
" People taking anti-coagulant medicine, those with hemophilia and those on dialysis are among those who should avoid using a jet injector as it could cause a bleeding problem."
"Bruising and pain is a common complaint that users mention in messages on Internet newsgroups. Jonathan Mills, associate professor of computer science at Indiana University and the leading on-line proponent of jet injectors, says that he initially had some bruising. He attributes it mainly to using too light a setting."
These are just a few of the comments that were posted on that site, hopefully they help shed a bit of light on what you are experiencing.
Also, search for yourself using your favorite website search engine, like Yahoo.com, or google.com they will turn up many sites that you can explore and learn new stuff about. Good luck!
Chrome
I wish I could help you with this one. We have never used this medi jet injector for my son. Perhaps you could contact the company or look on their website. Others may respond who may have more knowledge than I.
Have a wonderful day.
Carol
I'm guessing that your thighs are lean and a bit muscular. I haven't used the medijector for insulin, but did test one some years ago. I sort of remember reading that bruising can occur.
You might consider trying other injection sites when you use the medi-jector, sites that have a bit more fat to work with. Our insulin injections do their best work when they go into a layer of fat. I've had Type 1 for ~35 years and haven't taken shots into my thighs for, hmmm... I'd estimate about 20 years. Shots seemed to hurt & bruise more there than in my upper arm (fleshy part), abdomen or butt.
With some injection devices we can also adjust how hard we press the device against our skin. Try using the least pressure that still delivers the insulin.
It's hard enough to take shots & test, without having to also deal with bruises & bleeding reguarly. I'm not a physician, but I hope this info helps you. Let us know how you're doing, okay?