2006 ford escape not charging

i have an 06 escape recently changed the battery
and alternator bc the car was stalling while driving.
finaly brought it too a mechanic said alternator and
battery are good he ran it for an hour or so too see
if it would shut off...nope was fine of course at the
mechanic. that was monday so through out the
week it was fine. saturday comes theft light turns
on for ab 30 seconds than turns off while driving.
than battery light comes on and stays on. doesnt
seem too be the alternator bc its charging my car
for an entire week. now onto the following monday
car will not start it clicks but doesnt start. this car is
a mystery and seems everyone has this issue but
no answer too the problem. pls someone help