Invega comes in a once a month injectable form as well (Invega Sustenna) if you want to try that first before committing to three months (Invega Trinza)
but if you think the Invega is making you faint I wouldn't risk it. I was on Invega Sustenna and had minor allergic reactions (getting progressively worse with each injection) to it and waiting for the effects to wear off can be a bit much. I would make rule out Invega being the cause of the syncope before putting 1-3 months worth of it in your system.
Also be warned that different people metabolize meds at different rates so if you metabolize meds a little faster you might become symptomatic before your next injection is due.