likely the brand. BA is a solvent used when making aas injects and maybe yours has too much. my deca has never hurt. if anything iv used it to cut down high mg/ml gear that did have some sting to it
Like everyone above me has mentioned your gear likely has too much BA content, when your lab does this it's almost always due to sterility issues with their product/ production.
Stay away from that specific PED for a while it sounds PROBLEMATIC to say the least.
Other factor would be type of oil they used but then again it shouldn't factor out too much on the Richter scale.
Painful oils could be sesame oil, safflower, and cotton seed.