He has forbidden you only Al-Maytatah (meat of a dead animal), blood, the flesh of swine, and any animal which is slaughtered as a sacrifice for others than Allah (or has been slaughtered for idols etc. or on which Allah's Name has not been mentioned while slaughtering). But if one is forced by necessity, without wilful disobedience, and not transgressing, then, Allah is Oft-Forgiving, Most Merciful.