gearbox trouble?

hey people!! i bought a pug206 and im havin trouble,here goes..me and my brother in law replaced the lower arms on both sides the other day coz they were shot!! wen we put the new ones on the passenger side drive shaft came ouot(bit too easy if you ask me)wen we put it back in something wasnt right??it didnt seem to click in to place or sit in its housing properly???since then-wen i reverse it doesnt sound nice!! also after reversing and i go forward-it makes a clicking sound coming from the engine for a few metres then stops?? also the engine light has just come on and im wondering if its all ralated??please help me as its doin my sweed in!!i have a lil boy due in2weeks so want to make sure he is going to be safe. Thanks guys.james