Does pulmonary embolism have warning signs first? i'm not having symptoms but i've been on bed rest and trying to get back on feet slowly.

Yes: chest pain and shortness of breath (off and on). You have to sit down with your doctor and review medications and potential predisposing conditions you have that might put you at risk (for example contraceptives)

Chest pain, SOB: Signs of pulmonary embolism include chest pain and shortness of breath. This is an emergency. Preventive steps while on bed rest, aside from taking anticoagulant medication, include frequently flexing and extending the ankles, wearing compression or support stockings, and having the use of a pneumatic compression device. When able, get up and move around as much as possible. Hope that helps.