Banger -
don't worry about the small bumps, unless they become overly warm and/or inflamed.
If you want to encourage them to go away next time you shoot, massage the area with moderate pressure right after injection. This helps encourage your injected substance to disperse among the muscle tissue rather than forming a large pocket of oil and gear which can look like the lump you've described.
As far as splitting injections, you don't really need to split them up unless you're doing injections of more than 2mL per site. If you were doing 2mL deca, 2mL sust, 1mL winny, you could inject 1 in your delt, 1 in your quad, and inject the 1mL winny in your glute to minimize possible pressure on your sciatica (don't hit that MF; it hurts like nobody's business... never done it myself, but I've seen some of the boys walking like they had cerebral palsy for a couple of days).
Have a good one; happy sticking!
-M