The phrase is "apud milites questus fratrem sibi insidias comparare". I know all the words individually but for some reason, the sentence just is not coming together in my mind.
To give some context, the first section of the passage I'm working on is about Antoninus, the son of the emperor Severus. Based on my translation, as a young boy, he was very compassionate and pleasant but grew into a cruel young man. After the death of his father, he despises his brother for his humbleness. The phrase directly following the one I'm asking about says that Antoninus sent men who were to kill his brother to the palace, if that helps in any way.
From what I can tell, Antoninus complained ("questus") about something while with soldiers ("apud milites" - among the soldiers), possibly about obtaining ("comparare" - to obtain, possibly) a plot ("insidias") related to getting rid of his brother ("fratrem"). Not sure where "sibi" fits in, though. I am only a Year 12 Latin student as well and A-Level translations have been beyond my comfort zone so far, so what I've said so far may be wrong.