Dude , I bet the reason why you got this lump is because you injected too fast, you pierced the skin too fast , and injected too fast and pulled out too fast.
It's possible you hit a nerve or a vein or something in there. You gotta do it slow man in order to avoid this. The faster you pierce the skin and inject, the more risk you will get having a bruise and scar and LUMPS. If you do it Super slow at a snails pace, you will NOT GET ANY BRUISE, ANY SCAR OR ANY LUMPS OR ANY BLOOD IT WILL BE FLAWLESS AS IF YOU NEVER INJECTED.
It's about doing it SLOW and it's also about BA content. But most likely injecting slow, BA content or Oil content DO NOT CAUSE LUMPS. Only a quick pierce of the skin with a sizable pin needle rupturing the skin and hitting a nerve or something in there and injecting too fast and pulling out too fast will cause a SCAR or lump immediatly to form.
You gotta do it slow, try it next time but doing it super slow, you'll see you wont get any lumps or pain or blood or scarring. And don't listen to anyone who says " your a pussy for doing it so slow" screw them, they are the stupid pussies and morons who have bunch of scars and lumps all over the place for being so stupid and reckless.
Do it smart, do it slow and do it clean and use alcohol swab to clean the site before and after you inject. And you will see it will be flawless. There wont be any lumps or anything.